Phase 1 of the fight involves fighting both Twins at once. When you kill one of the Twins, she will merge with her sister, who will gain some of her abilities, and phase 2 will begin. Killing Alythess before Sacrolash is the easier order. As of June 19 2008, Bornakk confirmed that killing order would no longer matter, but before that date, killing Alythess second and Sacrolash first would give more loot. As of the arrival of patch 2.4.3, the Twins now always drops the version with the most loot.

Dark Strike, dealing 450 Shadow damage every 2 seconds and slowing the target by 10% for 10 seconds. Stacks up to 5 times, the timer is updated on each new stack.

Shadow Nova - A nova type attack dealing 3238 to 3762 Shadow damage to every player within a 10 yard radius of the player it is casted on. Usually targets the player with the 2nd highest aggro on Alythess. Cannot occur more than once every 30 seconds.

Shadow Image - Lady Sacrolash randomly spawns multiple Shadow Images which die on their own after a short amount of time. They cannot be targeted, and will typically only do one of their available attacks on a random player:

Melee attacks causes the target to become Dark Touched, and applies Dark Strike.

Pyrogenics - A buff on Alythess increasing all Fire damage of spells and effects done by her with 35%.

Flame Touched - A stackable debuff causing 300 Fire damage every 2 seconds. Stacks up to 20 times or a maximum of 6000 per 2 sec. Can only be removed by being hit with Shadow damage from either Twin.

Conflagration - A debuff placed on a target dealing 1600 Fire damage to everyone within 8 yards and also causes them to gain the debuff as well. In addition, it confounds the target for 6 seconds and scorches players within 8 yards for 1600 Fire damage each second. Usually casted on the player that is 3rd on Sacrolash's aggro.

Have someone dispel, purge or Spellsteal Pyrogenics from Alythess whenever she casts it on herself. The tank must be constantly moving to avoid the fire patches Blaze leaves behind. Let your healers put HoTs on people affected by Flame Sear and Conflagration. The tank taking Alythess must be constantly healed, since Flame Touched does a lot of damage as it stacks.

Sacrolash must have at least two tanks when Confounding Blow is used, so that the other tank can regain the aggro that was lost by the current tank. Have everyone spread out so that they are not hit by Shadow Nova, although this can also be used to remove the Flame Touched debuff. Dark Strike isn't much of a problem, except for when the Sacrolash tank needs to switch sides due to the movement speed decrease.

At level 80, the high dps, hp and healing increases make this fight much easier than at 70, however, to ensure a smooth kill, some rules should still be followed, including:

1) Dps should still concentrate on burning down Grand Warlock Alythess and then Lady Sacrolash.

2) The 2 melee tanks should still be tanking Lady Sacrolash up the ramp (but never out of line of sight) and at distance from the other raid members so that Conflagration doesn't spread more than it needs to.

3) Any of the melee tanks who are not human should still equip their PVP trinkets in case one is hit with Conflagration and the other with Confounding Blow (so that at least one tank is not disoriented and is able to continue tanking Lady Sacrolash).

4) Considering the raid composition, it would be best to assign a high dps/tps caster (such as a warlock) to tank Grand Warlock Alythess. [NOTE: At TotC-gear levels, it is often not necessary to have a caster remote-tank this. The damage can be healed through as she is burned down.]

5) Assign a mage or shaman to spellsteal/purge Pyrogenics from Grand Warlock Alythess if possible as it will make the healer's jobs easier.

6) Depending on dps performance, Dark Touched / Flame Touched should not stack too high for it to be a serious concern anymore.

At 85 the fight will go much faster, casters are still advised to stay on the ledge and any conflagrate targets to run away from the raid.

/Patch 3.0.2 (14-Oct-2008): All raid dungeons from Karazhan to Sunwell Plateau as well as the outdoor encounters of Doom Lord Kazzak and Doomwalker have been adjusted and now all creatures and bosses have less health points and do less damage.Health was reduced from 3,000,000 to 2,018,000 each

Patch 2.4.3 (2008-07-15): Creatures in the area around Grand Warlock Alythess and Lady Sacrolash will no longer spawn while the twins are in combat.

Patch 2.4.3 (2008-07-15): The Eredar Twins will now award the same items regardless of which order they are killed in.

Patch 2.4.2 (2008-05-13):Lighting in the room has been made darker with the removal of the candlesticks.